Alpine Meadows, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

086
FXUS65 KREV 211128
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
328 AM PST Thu Nov 21 2024


.SYNOPSIS...

* Rain showers will continue across NE CA today with gusty breezes
  this afternoon.

* Another round gusty winds, rain and mountain snow arrives Friday
  night into Saturday with Sierra travel impacts likely over the
  weekend.

* A colder storm pushes in Sunday through Tuesday with more snow and
  gusty winds ahead of a busy holiday travel week.

&&

.DISCUSSION...
Stormy weather continues through the weekend into early next week.
Keep an eye on road conditions if you have holiday travel plans.
Breaks in storm activity will be this afternoon and evening, and
then again late Saturday into midday Sunday.

Snow levels climbed to around 9000-9500 feet overnight with most
precipitation transitioning from snow to rain. Rain showers will
continue across northeastern California this morning with a brief
recession in the precipitation as the main moisture plume shifts
northward this afternoon into early Friday morning. Persistent
rainfall in Lassen and Plumas County will result in some flooding
concerns over the weekend (see Hydrology section below for more
details). For much of western Nevada, including the Greater Reno-
Carson City-Minden area, we will remain on the dry side with
afternoon breezes and only the occasional sprinkle of rain through
the early morning.

The next wave of wind/rain/snow pushes in Friday into Saturday.
Latest simulations are leaning toward a stronger burst of winds
ahead of the precipitation. Blended guidance is highlighting a 40-
50% chance for wind gusts exceeding 50 mph for Friday afternoon and
evening, particularly along the Highway 395 and Interstate 580
corridor. While the winds don`t appear as strong as Wednesday`s wind
event, we are seeing some signals for downslope enhancement that may
boost the wind gusts, especially for wind prone locations. Plan on
another round of gusty winds with impacts to backcountry recreation,
hazardous lake conditions, high profile vehicle travel restrictions
and aviation turbulence. This next incoming round of precipitation
has better potential for spillover into western Nevada and southward
to the Eastern Sierra. Snow levels start a touch high (7500 ft)
Friday morning, but then drop to near 5500 ft by late Saturday
morning. Sierra pass travel impacts will become a concern Saturday
morning. A foot or two of snow is possible along the Sierra crest
from late Friday into Saturday with a 20% chance of highest peaks
receiving 3 feet or more of snowfall. For Sierra communities near
lake level, blended guidance shows a 35-45% chance of at 2 inches of
snow.

The last round of the storm arrives late Sunday into Tuesday
bringing another round of precipitation to the Sierra and western
Nevada. This wave has consistently been colder than the previous
waves and holds the best potential for accumulating snowfall.
Blended guidance shows a 30-40% chance of 3 feet of snow along the
Sierra crest, a 25-35% chance of 12 inches of snow in Sierra
communities, like Mammoth and South Lake Tahoe, and only a 10-15%
chance of an inch of snow for lower western NV areas by early
Tuesday morning. The liquid storm totals with this storm are not
nearly as impressive as the Friday-Saturday system, but the cold air
and lower snow levels will allow for those higher snow totals to
actualize.

-Edan


&&

.AVIATION...

Precip: Light rain will continue at KTRK and KTVL. KRNO/KCXP/KMEV
will remain shadowed by the mountains and dry through Thursday.
Heavier precipitation band will shift northward tonight with light
showers possible at KTRK. Next round of heavier precipitation
arrives around 18a Friday and will persist through Sat 18z.
Accumulations will be possible at Sierra terminals after Sat 0z.

Winds: Strong southwest FL100 winds will continue today and into
Saturday morning around 50-60 kt. Surface wind gusts will remain
breezy today at around 20-25kts. Stronger surface winds will develop
Friday afternoon into early Saturday morning with gusts 30+kts
possible.

The storm arriving on Friday will bring liquid water storm totals
nearing 2-3" for along the Sierra crest, with a 30-40% chance of 2+
inches of snow for KTRK/KTVL/KMMH by midday Saturday. In addition,
look for mountain obscurations during periods of MVFR/IFR conditions
in rain/snow for Sierra and far western NV terminals.

-Edan

&&

.AVALANCHE...

An atmospheric river will bring gusty winds and periods of snow to
the Sierra through early next week:

* Snow levels will remain at 7500-8500` before falling to near 5000-
  5500` on Saturday afternoon.

* First round of snow totals (through Thursday): 8-12" above 7000`
  north of Tahoe, little to no accumulation elsewhere.

* Second round of snow totals (Friday and Saturday): 12-24" along
  the Sierra crest with a 20% chance of highest peaks reaching 3
  feet of snow in Mono County.

* Third round of snow totals (Sunday through Tuesday): Colder storm
  with a 30-40% chance of 6+" of snow at lake level, 50-70% chance
  of a foot or more along the Sierra crest. Confidence is low on
  this, however.

* Strong ridgetop gusts of 60-90 mph will continue into the weekend
  before weakening.

-Salas

&&

.HYDROLOGY...

An atmospheric river is bringing heavy rainfall across northern CA.
This will result in water ponding in poor drainage areas and rapidly
increasing flows along rivers and streams throughout the area today
through late Friday or early Saturday.

Flooding is of the greatest concern in areas of Lassen and Plumas
counties, where the combination of longer duration rainfall and
lower elevation watersheds are likely to lead to minor flooding of
the Susan River as well as small creeks and streams in the area.
Flooding concerns diminish somewhat to the south, and no other
mainstem rivers are forecast to flood, but minor flooding of small
creeks and streams is possible from Lake Tahoe north.

Recent burn areas, especially north of Lake Tahoe, are a concern for
minor flooding, exacerbated by the transport of ash, sediment, and
debris that may obstruct drainage areas.

There is considerable uncertainty in the hydrologic response due to
(1) range in the precipitation forecast and (2) snow levels with
varying precipitation type and transitions from snow to rain and
back to snow again from today into the weekend. Additional
consideration should be given to the fact that at storm onset soils
will be dry with generally low streamflows, which will delay and
mute streamflow responses initially. Keep an eye on river forecast
updates at cnrfc.noaa.gov.

-Bardsley

&&

.REV Watches/Warnings/Advisories...
NV...Winter Storm Warning from 10 AM Friday to 10 PM PST Saturday
     NVZ002.

     Lake Wind Advisory until 4 AM PST early this morning NVZ002.

     Wind Advisory from 10 AM to 10 PM PST Friday NVZ001-003.

CA...Winter Storm Warning from 10 AM Friday to 10 PM PST Saturday
     CAZ071-072.

     Lake Wind Advisory until 4 AM PST early this morning CAZ072.

     Winter Storm Warning from 4 PM Friday to 10 PM PST Saturday
     CAZ073.

     Flood Advisory until 12 PM PST Saturday CAZ071.
&&

$$